Visit Canada: TRV or eTA?

Which one do I need? TRV or eTA. You only need one of them, not both

Citizens of visa-exempt countries intending to travel to Canada by air are expected to have applied for an obtained an electronic Travel Authorization (eTA) before their departure to Canada. 

Exception: Citizens of the United States do not require a TRV or an eTA, but Green Card holders in the United States, require an eTA to come to Canada, regardless of their nationality.

If you are NOT a citizen from a visa-exempt country, you WILL need a TRV to enter Canada.

The following foreigners need either a TRV or an eTA: